Taco Bout Fertility Tuesday · Patient Tool

hCG Rise Calculator

Enter your beta hCG results and when each blood draw was done. See how fast the number rose and how that compares with published minimums.

Last reviewed: November 2026 · v2.0

Read this first. This tool compares your numbers with published averages. It cannot tell you whether your pregnancy is healthy, and it cannot diagnose a miscarriage or an ectopic pregnancy. A slow rise does not by itself mean a miscarriage or an ectopic pregnancy, and a normal rise does not rule either one out. Always talk with your clinic for interpretation.
1 Your blood tests
Test 1
mIU/mL
Test 2
mIU/mL

Two tests are enough; add more if you have them. Use the time the blood was drawn (the appointment time is fine if you don’t know). Use results from the same lab when you can. mIU/mL and IU/L are the same unit.

2 One more question
What the numbers mean, and what they can’t tell you

Minimum expected rise over 48 hours. In a study of 285 women with early-pregnancy symptoms who went on to have a healthy pregnancy in the uterus, the slowest 1% rose by at least 49% over two days when the first number was under 1,500 mIU/mL, at least 40% when it was 1,500 to 3,000, and at least 33% when it was over 3,000 (Barnhart 2016; used in ACOG Practice Bulletin 193). The bar compares your rise, adjusted to 48 hours, with the minimum for your starting level.

A slow rise is not a diagnosis. About 1 in 100 healthy pregnancies rise more slowly than these minimums. A published series of healthy pregnancies after embryo transfer included rises as low as 22% to 27% over 48 hours.

A normal rise does not rule out a problem. Roughly 1 in 5 ectopic pregnancies have an hCG rise that looks like a healthy pregnancy, so your clinic also uses ultrasound, symptoms and repeat testing.

Falling numbers. About 95% of early miscarriages show a fall of 21% to 35% or more over two days (ACOG). A fall still needs your clinic’s follow-up, because an ectopic pregnancy can also have a falling number and is monitored until hCG reaches zero.

Other cautions. The ranges come from studies of 48-hour intervals, so no range is shown when your draws are less than 24 or more than 96 hours apart. Levels rise more slowly as they climb, so doubling time is less meaningful once results are in the thousands. Different labs can report slightly different numbers.

How the math works

Doubling time = hours between tests × ln 2 ÷ ln(second ÷ first)

Rise per 48 hours = (second ÷ first)48 ÷ hours − 1

Both assume steady exponential growth between draws. If you enter more than two tests, each pair of neighboring tests is shown separately, and the starting level for each pair decides which minimum applies.

Sources and change log
  • Barnhart KT, Guo W, Cary MS, et al. Differences in serum human chorionic gonadotropin rise in early pregnancy by race and value at presentation. Obstet Gynecol 2016;128:504-11.
  • ACOG Practice Bulletin No. 193, Tubal Ectopic Pregnancy (2018): minimum 48-hour rise by starting level; 21% to 35% fall in early loss.
  • Barnhart KT, et al. Decline of serum hCG and spontaneous complete abortion: defining the normal curve. Obstet Gynecol 2004;104:975-81.
  • Case series of viable pregnancies after embryo transfer with low rates of rise: PMC8244357 (F&S Reports 2021).
  • Ectopic pregnancies with a healthy-looking rise (roughly 15% to 20%): reported in the clinical literature; exact figures vary by study.

Change log. v2.0, November 2026: added color range bar against published minimums, optional extra blood tests, clinic-interpretation guidance. v1.0: first release.

Educational tool from Taco Bout Fertility. It is not medical, legal or financial advice and does not create a doctor–patient relationship. Nothing you type leaves your device.

Talk with your own fertility doctor about your dates, your protocol and your costs.